A window-integrated antenna of this type is described in German Patent No. DE 36 19 704, for example, in regard to a diversitary antenna arrangement, in which the window pane of the motor vehicle is used in conjunction with one or more line structures and the metallic frame surrounding the window pane, as the antenna for the reception of LMS and USW signals. In that case, two antenna conductors are positioned on the window pane of the motor vehicle, of which the one antenna conductor includes three conductor sections. The connection points of the two antenna conductors are situated in a corner of the window pane, in proximity to which the connecting network is also positioned, which has three inputs. Two of the inputs are each connected to one of the connection points of the two antenna conductors. The third input is assigned to the ground point of the metallic frame. The inputs connected to the connection points of the antenna conductors, together with the ground point, in each case form a monopole connection.
A disadvantage of the conventional window-integrated antenna is that the line structures of the antenna conductor which are used are optimized either for LMS reception or for USW reception. In this case, very long line structures are frequently used for the LMS reception, which have no resonance response for USW frequencies. Line structures whose length corresponds to ¼ of the operating wavelength in the USW range and which act in this context as the monopole are used for USW reception. However, these are again subject to the disadvantage that they do not have adequate reception response for LMS frequencies. If the line structures of the antenna conductors are integrated into a windshield made of laminated safety glass, they also always have an interfering effect, since they are in the visible area.
A further window-integrated antenna for motor vehicles is described in German Patent No. DE 92 17 173. Provided therein is an antenna structure which does not visually interfere in the window pane of the motor vehicle and which considers monopoles exclusively for the reception of LMS and diversitary USW signals, but it has been shown that the reception of LMS signals is nonetheless inadequate using antenna structures of this type. In order to allow reliable reception of LMS signals, antennas which may be positioned as a separate antenna on a different spatial point of the motor vehicle, on the bumper or on the spoiler, for example, are therefore frequently additionally used in motor vehicles.
However, the conventional window-integrated antennas frequently have the disadvantage that by taking the reception of different radio signals into consideration, the line structures which are used have at least two line ends such that, based on the requirement for a connection point, an electrical connection must be established in the region of the window pane of the motor vehicle. While this may be performed in a simple manner for a window pane made of single-layer safety glass, it is not possible to electrically connect multiple separate antenna conductors in a window pane made of laminated safety glass, since the manufacturing reliability of the window pane is no longer ensured because of possible air inclusions.